Vertical-type filling and packaging machines are known which produce packages including contents in the form of a liquid or a paste having no specific shape held therein.
Such a vertical-type filling and packaging machine successively produces packages by forming a long length of sheet film such that both edges thereof in a width direction coincide and feeding the film downward. The vertical-type filling and packaging machine has a vertical seal mechanism which heat-seals the edges of the formed film along a longitudinal direction of the film to shape the film into a tubular shape, a supply pipe for supplying contents into the tubular shaped film, and a horizontal seal mechanism which heat-seals the film throughout the width thereof in order to seal in the contents supplied in the film.
The horizontal seal mechanism has a pair of seal bars moved toward or away from each other and placed opposite to each other across a path through which the film passes. The paired bars sandwich the film, and heats and pressurizes the film to heat-seal the film in the width direction.
The horizontal seal mechanism also has a pair of cooling bars placed opposite to each other across the path through which the tubular film passes. Similarly to the seal bars, the cooling bars are moved toward or away from each other and sandwich and pressurize the film to promote cooling of the portion of the film that was heated by the seal bars. One of the paired cooling bars is provided with a cutter which is moved toward or away from the other cooling bar. While the cooling bars are closed, the cutter is moved forward to cut the portion of the film that is sandwiched by the cooling bars along the width direction.
In conventional vertical-type filling and packaging machines, improved quality of produced packages is sought by refining the arrangement, the operation and the like of the components of the horizontal seal mechanism such as the seal bars and the cooling bars.
For example, Japanese Patent No. 2598879 (Patent Document 1) has disclosed a filling and packaging machine which includes a cooling bar incorporated in each of a pair of seal bars. Specifically, each of the seal bars movable toward or away from each other is provided for each of a pair of support members placed opposite to each other across a path through which film passes. The cooling bar is provided for each of the support members such that the cooling bars are positioned apart when the seal bars are placed at a forward pressurization position, and as the seal bars are moved backward, the cooling bars are moved toward the position where they perform pressurization at the same position as the pressurization position of the seal bars. One of the two cooling bars is provided with a cutter for cutting the film in a width direction.
During a process of sealing contents by the horizontal seal mechanism, the feeding of the film and the supplying of the contents are temporarily stopped. In this state, the seal bars are moved forward to heat and pressurize the film to perform heat sealing in the width direction. The seal bars are then moved backward. This causes the cooling bars to move and pressurize the heat-sealed portion of the film. The heat-sealed portion of the film is cooled by the cooling bars and solidified, and cut by the cutter in the width direction. After the cooling and the cutting of the tubular film by the cooling bars, the seal bars are moved forward to an intermediate position to release the film from the cooling bars. The abovementioned operations result in a package including the contents therein. Then, the downward feeding of the film and the supplying of the contents are restarted, and the series of operations described above is repeated.
International Publication WO 2005/105578 (Patent Document 2) has disclosed a filling and packaging machine in which a pair of seal bars and a pair of cooling bars are attached to a support member which is movable upward and downward. The pair of seal bars are placed opposite to be movable toward or away from each other. The pair of cooling bars are placed opposite to be movable toward or away from each other under the seal bars. One of the cooling bars is provided with a cutter for cutting a film in a width direction.
In the filling and packaging machine disclosed in Patent Document 2, for sealing in contents by a horizontal seal mechanism, the seal bars are driven to heat-seal the film in the width direction while the feeding of the film and the supplying of the contents are temporarily stopped. The seal bars are then moved backward and the support member is moved upward. The upward movement of the support member causes the pair of cooling bars to be placed at the same level as that of the heat-sealed portion of the film. After the upward movement of the support member, the cooling bars are closed to solidify the heat-sealed portion of the film and to cut the tubular film in the width direction. Then, the cooling bars are opened to provide a package including the contents therein. Thereafter, the support member is moved downward, the downward feeding of the film and the supplying of the contents are restarted, and the abovementioned series of operations is repeated.
As described above, the filling and packaging machine described in Patent Document 1 has the structure in which the cooling bars are incorporated into the seal bars, so that the heat-sealed position of the film is hardly displaced from the cutting position thereof. Such a horizontal seal mechanism, however, has a complicated structure which limits the usable shapes in the seal bars and the cooling bars to some extent. In production of packages, the seal bars and the cooling bars may need to be changed depending on the shape and the size of the packages to be produced or the material of the film. If the usable shapes of the seal bars and the cooling bars are limited, a wide variety of packages cannot be produced.
In the filling and packaging machine described in Patent Document 2, since the seal bars and the cooling bars are driven independently, it is easy to form the bars to be replaceable individually and thus a wide variety of packages can be produced. In the filling and packaging machine described in Patent Document 2, however, the feeding of the film and the supplying of the contents are stopped from the start of the heat sealing of the film to the opening of the cooling bars, that is, during the operation of the horizontal seal mechanism, as is the case with the filling and packaging machine described in Patent Document 1. To improve the manufacture efficiency of packages, it is advantageous to minimize the time period in which the feeding of the film is stopped.
Some of the vertical-type filling and packaging machines have a pair of film holders which are placed above seal bars to sandwich a film throughout the width thereof in order to perform heat sealing more stably by a horizontal seal mechanism. In the filling and packaging machine described in Patent Document 2, however, the whole horizontal seal mechanism including the seal bars and the cooling bars is moved upward in cooling the film. Even when the film holders are provided for the horizontal seal mechanism, the film holders cannot be functioned effectively since the film holders need to be opened in the upward movement of the horizontal seal mechanism. It is also contemplated that the film holders can be provided as a unit independent of the horizontal seal mechanism and be placed above the horizontal seal mechanism. In this case, however, the film holders need to be placed at a level determined by taking account of the upward moving distance of the horizontal seal mechanism, leading to an increase in the height of the filling and packaging machine.